Internal combustion engine



FIG. 1 is a front view of an internal combustion engine showing my new design.

FIG. 2 is a rear view thereof.

FIG. 3 is a left side view thereof.

FIG. 4 is a right side view thereof.

FIG. 5 is a top plan view thereof.

FIG. 6 is a bottom view thereof.

FIG. 7 is a right front perspective view thereof; and,

FIG. 8 is a left front perspective view thereof. 

The ornamental design for an internal combustion engine, as shown and described. 